The overall objective of the Feasibility of Retinoic Acid Treatment in Emphysema (FORTE) study is to conduct preliminary studies at 5 clinical centers preparatory to conducting a randomized, controlled, clinical trial on the efficacy of retinoic acid therapy in the management of emphysema. Objectives are to identify optimal patient populations, drugs and dosing schedules, and outcome measures for a large study, if indicated. This project serves as the Data Coordinating Center which will collect, verify, store, and analyze data from the Clinical Centers.